Stereo Camera Centering System Using Mirror Reflection
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Solution Overview
Problem
Existing methods for determining centering data for glasses fitting are time-consuming, require significant manual effort, and are challenging due to the need for precise camera alignment and subject positioning, which can be uncomfortable and difficult to maintain.
Innovation Solution
A method using a stereo camera system with fixed cameras positioned symmetrically around a mirror, where the subject looks into the mirror to establish a zero gaze direction, allowing simultaneous image capture and reducing the need for camera adjustment, with software correction for imaging errors and trigonometric calculations to determine lens visual points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cameras are placed at different heights with angled optical axes to capture images from multiple perspectives, then measurement precision is improved, but device complexity and alignment difficulty increase
Solution Approach 1:
Instead of positioning cameras at different heights and angles to achieve measurement precision, the patent inverts the approach by placing a single camera at eye level with the subject, using a mirror to capture the zero line of sight. This eliminates complex multi-camera alignment while maintaining measurement accuracy through the mirror reflection principle.
Solution Approach 2:
The patent introduces a mirror as an intermediary element between the camera and subject. The mirror enables the camera to capture the subject's zero line of sight without requiring complex angular positioning, simplifying the system while preserving measurement precision through optical reflection.
2Measurement precision
If multiple pupil positions are recorded to determine centering data, then measurement completeness is improved, but measurement time increases
Solution Approach 1:
The patent performs preliminary action by having the subject look into the mirror to automatically establish the zero gaze direction before the actual measurement. This pre-positioning of the line of sight eliminates the need for multiple sequential recordings of different pupil positions, reducing measurement time while ensuring data completeness.
Solution Approach 2:
The subject actively participates by looking into the mirror, which automatically establishes the correct zero line of sight without operator intervention. This self-service approach ensures accurate positioning while minimizing measurement time, as the subject's natural gaze direction is captured in a single recording.
3Measurement precision
If the subject is positioned close to the mirror for image capture, then measurement accuracy is improved, but subject comfort and natural posture deteriorate
Solution Approach 1:
The patent resolves the contradiction by changing the spatial dimension - instead of requiring the subject to be close to the mirror, the system captures images from a distance of 0.5 to 1 meter. The mirror's reflective property allows accurate zero line of sight capture at this comfortable distance, maintaining both measurement precision and subject comfort.
4Adaptability or versatility
If manual marking of measuring points is performed, then measurement flexibility is improved, but operator effort and time expenditure increase
Solution Approach 1:
The patent replaces the mechanical manual marking process with automated software-based identification. The system automatically detects and marks measuring points on the captured images, eliminating manual operator intervention while maintaining measurement flexibility. This substitution significantly improves operator efficiency and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces measurement time, minimizes operator and subject effort, and allows for accurate centering data determination without requiring cameras to be aligned to the subject's eye level, enabling a more comfortable and efficient glasses fitting process.
Implementation Method 1
The test subject looks at his own eyes in the mirror to assume the zero gaze direction (horizontal line of sight distance)
Implementation Method 2
A synchronous recording of at least the area of the test subject's face occupied by the spectacle frame is carried out simultaneously by all cameras of the stereo camera system
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for determining optical parameters of a test subject with measurement accuracy in order to adapt a pair of eyeglasses by means of a stereo camera system (4), a mirror (3) arranged at the height of the stereo camera system, and a data-processing and data output device, in which additionally the correction data of the cameras of the stereo camera system (4), the image scales of said cameras, and information about the position of said cameras in space are stored. The test subject (1) directs his view at the mirror image of his head arising in the virtual mirror plane (5) (null viewing direction), while both cameras simultaneously record an image of the region of the head of the test subject (1) provided with the eyeglass frame (2). The direction, distance, and height position of the optical data are determined means of the software and by using the stored correction data, image scales, and position information, wherein existent size changes and distortions due to position are offset by means of correction calculations. Thus, only one recording of the face of the test subject is required to determine the centering data of the pair of eyeglasses, whereby the measurement time and thus the time burden for the test subject are significantly reduced.